Handle invarient inside unsafeTextWithLength

Author: reixn

prettyprinter/src/Prettyprinter/Internal.hs

@@ -491,7 +491,9 @@ unsafeTextWithoutNewlines text = case T.uncons text of
 --      unsafeTextWithLength "😃" (realLength "😃")
 -- @
 unsafeTextWithLength :: Text -> Int -> Doc ann
-unsafeTextWithLength txt l = Text l txt
+unsafeTextWithLength txt l | T.null txt = Empty
+                           | l == 1 && T.length txt == 1 = Char (T.head txt) -- no wide character or control
+                           | otherwise = Text l txt
 
 -- | The empty document behaves like @('pretty' "")@, so it has a height of 1.
 -- This may lead to surprising behaviour if we expect it to bear no weight